JP2012067607A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a situation of EGR control valve opening not reaching minimum EGR control valve opening from occurring at a point of throttle valve opening reaching a minimum throttle valve opening during a deceleration period.SOLUTION: Target throttle valve opening and target EGR control valve opening are set during normal operation, a throttle valve and an EGR control valve are controlled, respectively and the throttle valve opening and the EGR control valve opening are decreased to the minimum opening XthMin, XegrMin during deceleration request. When a point Tegrc of the EGR control valve opening reaching the minimum opening is earlier than a point Tthc of the throttle valve opening reaching the minimum opening during the deceleration request, the target EGR control valve opening or target EGR gas amount set during the normal operation is increased.

Description

  The present invention relates to a control device for an internal combustion engine.

  Patent Document 1 discloses a period (hereinafter, referred to as “deceleration request is generated and the internal combustion engine is decelerated) in an internal combustion engine having a throttle valve and a so-called exhaust gas recirculation device (hereinafter referred to as“ EGR device ”). The throttle valve opening during this period (referred to as “deceleration period”) (hereinafter referred to as “throttle valve opening”) and the exhaust gas recirculation control valve (hereinafter referred to as “EGR control valve”) of the EGR device. (Hereinafter referred to as “EGR control valve opening”).

  In this control method, the opening degree of the accelerator pedal (hereinafter referred to as “accelerator pedal opening degree”) is monitored during the deceleration period, and a deceleration request is generated until the accelerator pedal opening degree becomes zero. The EGR control valve opening is controlled so that the target EGR rate set from the map is achieved while maintaining the throttle valve opening at the time (hereinafter referred to as “deceleration request generation time”). Then, when the accelerator pedal opening becomes zero, the throttle valve opening is reduced and the target EGR rate is set to zero, whereby the EGR control valve opening is reduced. According to Patent Document 1, the reason why the throttle valve opening and the EGR control valve opening are controlled in this way during the deceleration period in this control method is as follows.

  That is, a so-called EGR device is a device that introduces the exhaust gas into the combustion chamber by introducing the exhaust gas discharged from the combustion chamber into the exhaust passage into the intake passage. Here, since the exhaust gas is an inert gas, when the exhaust gas is introduced into the combustion chamber, the combustion temperature of the fuel in the combustion chamber decreases, thereby causing nitrogen oxides resulting from the combustion of the fuel in the combustion chamber. (Hereinafter referred to as “NOx”) is suppressed.

  On the other hand, the amount of exhaust gas introduced into the combustion chamber, that is, the amount of exhaust gas introduced into the intake passage by the EGR device (hereinafter referred to as “EGR gas”) increases, and as a result, the combustion chamber If the ratio of the amount of EGR gas to the amount of air sucked (hereinafter this ratio is referred to as “EGR rate”) increases, the ratio of air in the gas sucked into the combustion chamber decreases. Is likely to occur.

  Here, since the torque required for the internal combustion engine becomes extremely small during the deceleration period, the throttle valve opening is generally minimized in order to minimize the amount of air sucked into the combustion chamber. The opening degree (in many cases, the opening degree is extremely close to zero, and this opening degree is hereinafter referred to as “minimum throttle valve opening degree”). At this time, if the amount of EGR gas is maintained at the amount at the time when the deceleration request is generated, the EGR rate is significantly increased, and misfire occurs in the combustion chamber. In order to avoid this, when a deceleration request is generated, the EGR control valve opening is set to the minimum opening (in many cases zero) in order to minimize the amount of EGR gas (in many cases zero). Yes, this opening is hereinafter referred to as “minimum EGR control valve opening”.

  Here, a control method is adopted in which the throttle valve opening is started to decrease toward the minimum throttle valve opening at the time when the deceleration request is generated, and the EGR control valve opening is started to decrease toward the minimum EGR control valve opening. In this case, if there is a delay in the response of the EGR control valve, it takes time until the EGR control valve opening actually starts decreasing after the operation amount for decreasing the EGR control valve opening is input to the EGR control valve. As a result, there arises a situation in which the rate of reduction of the EGR gas amount is smaller than the intended rate of reduction, even though the rate of reduction of the air sucked into the combustion chamber is the intended rate of reduction. When such a situation occurs, the EGR rate is larger than the intended EGR rate while the throttle valve opening and the EGR control valve opening are decreasing toward the minimum throttle valve opening and the minimum EGR control valve opening, respectively. As a result, misfire may occur in the combustion chamber. In particular, when the throttle valve opening reaches the minimum throttle valve opening, when the EGR control valve opening does not reach the minimum EGR control valve opening, the throttle valve opening reaches the minimum throttle valve opening. Since the state in which the EGR rate is relatively high continues until the EGR control valve opening reaches the minimum EGR control valve opening, the possibility of misfire in the combustion chamber is high.

  According to the description in Patent Document 1, in order to avoid this, the throttle valve opening and the EGR control valve opening are controlled during the deceleration period as described above.

  However, in the control method described in Patent Document 1, a decrease in the throttle valve opening and a decrease in the EGR control valve opening are not started when the deceleration request is generated, but a certain time has elapsed since the deceleration request is generated. At the time (specifically, when the accelerator pedal opening becomes zero), a decrease in the throttle valve opening and a decrease in the EGR control valve opening are started, but these decreases are started simultaneously. Therefore, even if the throttle valve opening and the EGR control valve opening are controlled during the deceleration period according to the control method described in Patent Document 1, if the response of the EGR control valve is delayed, after all, the throttle valve While the opening and the EGR control valve opening are decreasing toward the minimum throttle valve opening and the minimum EGR control valve opening, respectively, the EGR rate becomes larger than the intended EGR rate, and as a result, in the combustion chamber Misfire may occur. Of course, there may be a situation where the EGR control valve opening does not reach the minimum EGR control valve opening when the throttle valve opening reaches the minimum throttle valve opening. Since the EGR rate remains relatively high from the time when the minimum throttle valve opening is reached until the EGR control valve opening reaches the minimum EGR control valve opening, misfiring occurs in the combustion chamber. Probability is high.

  Thus, in the control method described in Patent Document 1, anyway, there is a high possibility that misfire will occur in the combustion chamber.

  Further, when the EGR device is used for a long period of time, the speed at which the EGR control valve closes may be slower than the initial speed. In this case, according to the control method described in Patent Document 1, when the throttle valve opening reaches the minimum throttle valve opening, a situation occurs in which the EGR control valve opening does not reach the minimum EGR control valve opening. The possibility increases. As a result, there is a possibility that misfire may occur in the firing chamber between the time when the throttle valve opening reaches the minimum throttle valve opening and the time when the EGR control valve opening reaches the minimum EGR control valve opening. Get higher.

  Thus, in an internal combustion engine equipped with a throttle valve and an EGR device, the throttle valve opening and the EGR control valve opening decrease toward the minimum throttle valve opening and the minimum EGR control valve opening, respectively, during the deceleration period. During the operation, it is required to suppress the EGR rate from becoming larger than the intended EGR rate, and when the throttle valve opening reaches the minimum throttle valve opening after the deceleration request is generated, the EGR control valve The control method described in Patent Document 1 cannot meet such a demand, although it is also required to suppress the situation in which the opening does not reach the minimum EGR control valve opening.

JP-A-10-89130 JP 2010-138734 A JP 2006-194143 A JP 2001-82260 A JP 2004-316528 A JP 2003-3895 A

  Further, in an internal combustion engine equipped with an EGR device, as much EGR gas as possible during normal operation (that is, operation of the internal combustion engine when no deceleration request is generated) to suppress the generation of NOx in the combustion chamber. Is desired to be introduced into the combustion chamber. However, when the opening degree of the EGR control valve is increased in order to introduce a large amount of EGR gas into the combustion chamber, if a deceleration request is generated, it is necessary for the EGR control valve opening to reach the minimum EGR control valve. The time will be longer. For this reason, a situation in which the EGR control valve opening does not reach the minimum EGR control valve opening at the time when the throttle valve opening reaches the minimum throttle valve opening easily occurs. That is, although it is desired to introduce as much EGR gas as possible into the combustion chamber, the EGR control valve opening is set to the minimum EGR when the throttle valve opening reaches the minimum throttle valve opening during the deceleration period. It is necessary to maintain the EGR control valve opening during normal operation at an opening that can avoid the situation where the control valve opening is not reached. That is, from the viewpoint of avoiding a situation where the EGR control valve opening does not reach the minimum EGR control valve opening when the throttle valve opening reaches the minimum throttle valve opening during the deceleration period, The EGR control valve opening during operation has an upper limit opening.

  Since the EGR control valve opening during normal operation has an upper limit, the amount of EGR gas that can be introduced into the intake passage during normal operation also has an upper limit. However, as described above, from the viewpoint of suppressing the generation of NOx in the combustion chamber, it is desired that the amount of EGR gas during normal operation is as large as possible.

  Accordingly, an object of the present invention is to provide an EGR control valve with a minimum EGR control valve opening when the throttle valve opening reaches a minimum throttle valve opening during a deceleration period in an internal combustion engine having a throttle valve and an EGR device. An object of the present invention is to increase the amount of EGR gas introduced into the intake passage during normal operation as much as possible while suppressing the occurrence of a situation where the opening is not reached.

  A first invention of the present application is a throttle valve disposed in an intake passage and an exhaust gas recirculation device that introduces the exhaust gas into the combustion chamber by introducing the exhaust gas discharged from the combustion chamber into the exhaust passage. And an exhaust gas recirculation control device that controls an amount of exhaust gas introduced into an intake passage.

  In the present invention, when the operation state of the internal combustion engine is in a normal operation state other than the deceleration operation state, a target amount as the amount of air to be sucked into the combustion chamber is set as the target intake air amount and An amount to be targeted as the amount of exhaust gas introduced into the intake passage by the circulation control device is set as the target exhaust gas recirculation amount. The opening degree of the throttle valve and the opening degree of the exhaust gas recirculation control valve that can achieve the set target intake air amount and the target exhaust gas recirculation amount are the target throttle valve opening degree and the target EGR control valve opening degree, respectively. Set as Then, the throttle valve and the exhaust recirculation control valve are respectively controlled according to the set target throttle valve opening and target exhaust recirculation control valve opening.

  On the other hand, according to the present invention, when a request for deceleration operation of the internal combustion engine is generated, the opening degree of the throttle valve is reduced to the minimum opening degree and the opening degree of the exhaust gas recirculation control valve is reduced to the minimum opening degree.

  Here, in the present invention, the time when the opening degree of the exhaust gas recirculation control valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine is greater than the time point when the opening degree of the throttle valve reaches the minimum opening degree. If the opening of the exhaust gas recirculation control valve reaches the minimum opening, the operating state of the internal combustion engine is in a normal operation in a range that does not become slower than the time when the opening of the throttle valve reaches the minimum opening. The target exhaust gas recirculation control valve opening degree that is set as the opening degree of the exhaust gas recirculation control valve that can achieve the target exhaust gas recirculation amount that is set when the engine is in the state is increased, or the operating state of the internal combustion engine is normal operation The target exhaust gas recirculation amount set when the engine is in the state is increased.

  According to the present invention, when the opening degree of the throttle valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine, the situation in which the opening degree of the exhaust gas recirculation control valve has not reached the minimum opening degree. The effect that the amount of the exhaust gas introduced into the intake passage by the exhaust gas recirculation device can be increased as much as possible when the operation state of the internal combustion engine is in the normal operation state is suppressed.

  That is, according to the present invention, the throttle valve opening reaches the minimum opening when the opening degree of the exhaust gas recirculation control valve reaches the minimum opening when a request for deceleration operation of the internal combustion engine occurs. Since the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is increased every time a situation earlier than the point in time occurs, the exhaust gas recirculation device operates when the operating state of the internal combustion engine is in the normal operating state. The amount of exhaust gas introduced into the intake passage increases.

  On the other hand, when the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is increased, the deceleration operation request time point of the internal combustion engine is increased by the increase in the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount. Since the opening degree of the exhaust gas recirculation control valve is large, the time required for the opening degree of the exhaust gas recirculation control valve to reach the minimum opening degree after a request for deceleration operation of the internal combustion engine becomes longer. Thus, if the time required for the exhaust recirculation control valve opening to reach its minimum opening becomes longer, the exhaust gas recirculation will be reached when the throttle valve opening reaches that minimum opening. A situation in which the opening degree of the control valve does not reach the minimum opening degree easily occurs. However, in the present invention, the time when the opening degree of the exhaust gas recirculation control valve reaches its minimum opening degree when the request for deceleration operation of the internal combustion engine occurs is the time point when the opening degree of the throttle valve reaches its minimum opening degree. As soon as the target exhaust gas recirculation control valve or target exhaust gas recirculation amount is increased and the exhaust gas recirculation control valve opening reaches its minimum opening, the throttle valve opening is the minimum opening. The target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is increased within a range that does not become slower than the time point when the engine reaches the target value. For this reason, in the present invention, the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is increased, and the opening of the exhaust gas recirculation control valve is reduced to the minimum opening after the deceleration operation request for the internal combustion engine. Even if the time required to reach it becomes longer, when the throttle valve opening reaches its minimum opening, the exhaust recirculation control valve opening may not reach its minimum opening. Or at least suppressed.

  Therefore, according to the present invention, the opening degree of the exhaust gas recirculation control valve reaches the minimum opening degree when the opening degree of the throttle valve reaches the minimum opening degree after generation of the deceleration operation request of the internal combustion engine. The effect that the amount of exhaust gas introduced into the intake passage by the exhaust gas recirculation device can be increased as much as possible when the operation state of the internal combustion engine is in the normal operation state while suppressing the occurrence of a non-existing situation Is obtained.

  In the second invention of the present application, in the first invention, the exhaust gas recirculation control valve until the opening degree of the exhaust gas recirculation control valve reaches the minimum opening degree after generation of the deceleration operation request of the internal combustion engine is generated. When the closing speed of the exhaust gas is slower than the predicted closing speed of the exhaust gas recirculation control valve at that time, the opening degree of the exhaust gas recirculation control valve becomes the minimum opening degree after the request for deceleration operation of the internal combustion engine is generated. Even when the opening time is earlier than the time when the throttle valve opening reaches the minimum opening, the increase in the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is prohibited.

  According to the present invention, when the opening degree of the throttle valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine, the situation in which the opening degree of the exhaust gas recirculation control valve has not reached the minimum opening degree. The effect is that the amount of exhaust gas introduced into the intake passage by the exhaust gas recirculation device can be increased as much as possible when the operation state of the internal combustion engine is in the normal operation state while suppressing the occurrence more reliably. can get.

  That is, if the exhaust recirculation control valve closing speed is slower than the predicted exhaust recirculation control valve closing speed at that time, the actual exhaust recirculation control valve closing speed It means that it became late with it. Therefore, there is a concern that the valve closing speed of the exhaust gas recirculation control valve will become slower in the future. Despite these concerns, if the target exhaust gas recirculation control valve opening or target exhaust gas recirculation amount increases, the exhaust gas recirculation control valve closing speed actually becomes slower. There is a high possibility that the opening degree of the exhaust gas recirculation control valve does not reach the minimum opening degree when the opening degree of the throttle valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine. Become.

  However, according to the present invention, when the closing speed of the exhaust gas recirculation control valve is slower than the predicted closing speed of the exhaust gas recirculation control valve at that time, the exhaust gas recirculation is performed after the generation of the deceleration operation request of the internal combustion engine. Even if the time when the control valve opening reaches the minimum opening is earlier than the time when the throttle valve opening reaches the minimum opening, the target exhaust recirculation control valve opening or the target exhaust Increase in circulation is prohibited. Therefore, there is a situation in which the opening degree of the exhaust gas recirculation control valve does not reach the minimum opening degree when the opening degree of the throttle valve reaches the minimum opening degree after generation of the deceleration operation request of the internal combustion engine. The effect that the amount of exhaust gas introduced into the intake passage by the exhaust gas recirculation device can be increased as much as possible when the operation state of the internal combustion engine is in the normal operation state while being reliably suppressed. .

  Further, in the actual third invention, in the first or second invention, the exhaust gas recirculation until the opening degree of the exhaust gas recirculation control valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine is generated. When the valve closing speed of the control valve is faster than the predicted valve closing speed of the exhaust gas recirculation control valve at that time, the opening degree of the exhaust gas recirculation control valve is at its minimum opening after the deceleration operation request of the internal combustion engine is generated. Even when the opening of the throttle valve is earlier than the time when the opening of the throttle valve reaches the minimum opening, the increase in the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is prohibited.

  According to the present invention, when the opening degree of the throttle valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine, the situation in which the opening degree of the exhaust gas recirculation control valve has not reached the minimum opening degree. The effect is that the amount of exhaust gas introduced into the intake passage by the exhaust gas recirculation device can be increased as much as possible when the operation state of the internal combustion engine is in the normal operation state while suppressing the occurrence more reliably. can get.

  That is, when the exhaust gas recirculation control valve is controlled according to a certain control law, it is unlikely that the exhaust gas recirculation control valve closing speed gradually increases with time. Therefore, if the closing speed of the exhaust gas recirculation control valve is faster than the predicted closing speed of the exhaust gas recirculation control valve, there is a steady situation where the closing speed of the exhaust gas recirculation control valve is increased. It is considered that a sudden situation in which the valve closing speed of the exhaust gas recirculation control valve is increased rather than acting on the exhaust gas recirculation control valve has acted on the exhaust gas recirculation control valve. In this case, if such a sudden situation does not act on the exhaust gas recirculation control valve again, the exhaust gas recirculation control valve closing speed is higher than the predicted exhaust gas recirculation control valve closing speed at that time. There is a concern that should not be. Despite these concerns, if the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is increased, the valve closing speed of the exhaust gas recirculation control valve is actually predicted at that time. The exhaust gas recirculation control valve is opened when the throttle valve opening reaches its minimum opening after a request for deceleration operation of the internal combustion engine is generated. There is a high possibility that a situation where the degree does not reach the minimum opening degree will occur.

  However, in the present invention, when the valve closing speed of the exhaust gas recirculation control valve is higher than the predicted valve closing speed of the exhaust gas recirculation control valve at that time, the exhaust gas recirculation is performed after the generation of the deceleration operation request of the internal combustion engine. Even if the time when the control valve opening reaches the minimum opening is earlier than the time when the throttle valve opening reaches the minimum opening, the target exhaust recirculation control valve opening or the target exhaust Increase in circulation is prohibited. Therefore, there is a situation in which the opening degree of the exhaust gas recirculation control valve does not reach the minimum opening degree when the opening degree of the throttle valve reaches the minimum opening degree after generation of the deceleration operation request of the internal combustion engine. The effect that the amount of exhaust gas introduced into the intake passage by the exhaust gas recirculation device can be increased as much as possible when the operation state of the internal combustion engine is in the normal operation state while being reliably suppressed. .

It is the figure which showed the internal combustion engine to which the control apparatus of this invention was applied. (A) is the figure which showed the map utilized in order to acquire target throttle valve opening degree TXth based on engine speed NE and charging efficiency KL, (B) is engine speed NE and charging efficiency KL. It is the figure which showed the map utilized in order to acquire the target EGR control valve opening degree TXegr based on these. It is the figure which showed the mode of the change of the throttle valve opening degree Xth and the EGR control valve opening degree Xegr in case the EGR control valve closing time Tegrc is the same time as the throttle valve closing time Tthc. It is the figure which showed the map utilized in order to acquire predetermined delay time Td based on engine speed NE and charging efficiency KL. It is the figure which showed the mode of change of throttle-valve opening degree Xth and EGR control-valve opening degree Xegr in case EGR control valve closing time Tegrc is time earlier than throttle valve closing time Tthc. It is the figure which showed the mode of change of throttle-valve opening degree Xth and EGR control-valve opening degree Xegr in case EGR control valve closing time Tegrc is time later than minimum throttle valve closing time Tthc. (A) is the figure which showed the map utilized in order to acquire target intake air amount TGa based on engine speed NE and charging efficiency KL, (B) is engine speed NE and charging efficiency KL. FIG. 6 is a diagram showing a map used for obtaining a target EGR rate TRegr based on the above. It is the figure which showed an example of the routine which performs control of the throttle valve and EGR control valve according to 1st Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 1st Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 1st Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 1st Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 1st Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 2nd Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 2nd Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 2nd Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 2nd Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 3rd Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 3rd Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 3rd Embodiment of this invention. It is the figure which showed a part of example of the routine which performs increase of the target EGR control valve opening according to 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an internal combustion engine 10 to which the control device of the present invention is applied. The internal combustion engine 10 includes an internal combustion engine main body (hereinafter referred to as “engine main body”) 20, fuel injection valves 21 disposed corresponding to the four combustion chambers of the engine main body, and fuel supply to the fuel injection valves 21. And a fuel pump 22 for supplying fuel via a pipe 23. The internal combustion engine 10 further includes an intake system 30 that supplies air to the combustion chamber from the outside, and an exhaust system 40 that exhausts exhaust gas discharged from the combustion chamber to the outside. The internal combustion engine 10 is a compression self-ignition internal combustion engine (so-called diesel engine).

  The intake system 30 includes an intake branch pipe 31 and an intake pipe 32. In the following description, the intake system 30 may be referred to as an “intake passage”. One end portion (that is, a branch portion) of the intake branch pipe 31 is connected to an intake port (not shown) formed in the engine body 20 corresponding to each combustion chamber. On the other hand, the other end of the intake branch pipe 31 is connected to the intake pipe 32. A throttle valve 33 that controls the amount of air flowing through the intake pipe is disposed in the intake pipe 32. Further, an intercooler 34 for cooling the air flowing through the intake pipe is disposed in the intake pipe 32. Further, an air cleaner 36 is disposed at an end facing the outside of the intake pipe 32.

  The throttle valve 33 can variably control the amount of gas sucked into the combustion chamber by controlling the opening thereof. Specifically, the larger the opening of the throttle valve 33 (hereinafter, this opening is referred to as “throttle valve opening”), the more gas is sucked into the combustion chamber.

  On the other hand, the exhaust system 40 includes an exhaust branch pipe 41 and an exhaust pipe 42. In the following description, the exhaust system 40 may be referred to as an “exhaust passage”. One end portion (that is, a branch portion) of the exhaust branch pipe 41 is connected to an exhaust port (not shown) formed in the engine body 20 corresponding to each combustion chamber. On the other hand, the other end of the exhaust branch pipe 41 is connected to the exhaust pipe 42. In the exhaust pipe 42, a catalytic converter 43 having an exhaust purification catalyst 43A for purifying a specific component in the exhaust gas is disposed.

  Further, the internal combustion engine 10 includes a supercharger 35. The supercharger 35 includes a compressor 35A disposed in the intake pipe 32 upstream of the intercooler 34, and an exhaust turbine 35B disposed in the exhaust pipe 42 upstream of the catalytic converter 43. The exhaust turbine 35B is connected to the compressor 35A via a shaft (not shown). When the exhaust turbine main body 35C is rotated by the exhaust gas, the rotation is transmitted to the compressor 35A via the shaft, whereby the compressor 35A is rotated. The rotation of the compressor 35A compresses the gas in the intake pipe 32 downstream of the compressor, and as a result, the pressure of the gas (hereinafter referred to as “intake pressure”) is increased.

  Further, the internal combustion engine 10 includes an exhaust gas recirculation device (hereinafter referred to as “EGR device”) 50. The EGR device 50 includes an exhaust gas recirculation pipe (hereinafter referred to as “EGR passage”) 51. One end of the EGR passage 51 is connected to the exhaust branch pipe 41. That is, one end of the EGR passage 51 is connected to a portion of the exhaust passage 40 upstream of the exhaust turbine 35B. On the other hand, the other end of the EGR passage 51 is connected to the intake branch pipe 31. That is, the other end of the EGR passage 51 is connected to a portion of the intake passage downstream of the compressor 35A. Further, an exhaust gas recirculation control valve (hereinafter, this exhaust gas recirculation control valve is referred to as an “EGR control valve”) 52 that controls the flow rate of exhaust gas flowing through the EGR passage is disposed in the EGR passage 51. Further, an exhaust gas recirculation cooler 53 for cooling the exhaust gas flowing in the EGR passage is disposed in the EGR passage 51.

  The EGR device 50 controls the opening degree of the EGR control valve 52 to vary the amount of exhaust gas introduced into the intake passage 30 via the EGR passage 51 (hereinafter, this exhaust gas is referred to as “EGR gas”). Can be controlled. Specifically, the larger the opening of the EGR control valve 52 (hereinafter, this opening is referred to as “EGR control valve opening”), the greater the EGR gas amount.

  An air flow meter 71 for detecting the flow rate of air flowing through the intake pipe is attached to the intake pipe 32 downstream of the air cleaner 36 and upstream of the compressor 35A. In addition, a sensor (hereinafter referred to as “intake pressure sensor”) 72 for detecting intake pressure is attached to the intake branch pipe 31. The engine body 20 is provided with a crank position sensor 74 for detecting the rotational phase of the crankshaft.

  The internal combustion engine 10 includes an electronic control device 60. The electronic control unit 60 includes a microprocessor (CPU) 61, a read only memory (ROM) 62, a random access memory (RAM) 63, a backup RAM (Back up RAM) 64, and an interface 65. The fuel injection valve 21, the fuel pump 22, the throttle valve 33, and the EGR control valve 52 are connected to the interface 65, and control signals for controlling these operations are given from the electronic control unit 60 through the interface 65. It is done. The interface 65 includes an air flow meter 71, a pressure sensor 72, a crank position sensor 74, and an opening degree of the accelerator pedal AP (that is, an amount of depression of the accelerator pedal AP, hereinafter referred to as “accelerator pedal opening degree”). Is also connected to the accelerator pedal opening sensor 75, a signal corresponding to the flow rate detected by the air flow meter 71, a signal corresponding to the pressure detected by the supercharging pressure sensor 72, and a crank position sensor 74. A signal corresponding to the detected rotational phase of the crankshaft and a signal corresponding to the depression amount of the accelerator pedal AP detected by the accelerator pedal opening sensor 75 are input to the interface 65.

  The intake air pressure is calculated by the electronic control unit 60 based on the signal corresponding to the pressure detected by the intake pressure sensor 72, and the engine based on the signal corresponding to the rotational phase of the crankshaft detected by the crank position sensor 74. The number of revolutions (that is, the number of revolutions of the internal combustion engine 10) is calculated by the electronic control unit 60, and the accelerator pedal opening degree is calculated based on the signal corresponding to the depression amount of the accelerator pedal AP detected by the accelerator pedal opening degree sensor 75. Calculated by the control device 60.

  Next, control of the throttle valve and the EGR control valve when the operating state of the internal combustion engine is in a normal operating state other than the deceleration operating state will be described. The “decelerated operation state” means “the internal combustion engine when the accelerator pedal opening decreases relatively large (particularly, the accelerator pedal opening becomes zero) and the torque required for the internal combustion engine decreases relatively large. Means "operating state". In the following description, “engine operating state” means “operating state of the internal combustion engine 10”, “intake air amount” means “amount of air sucked into the combustion chamber”, and “EGR”. “Rate” means “ratio of the amount of EGR gas to the amount of gas sucked into the combustion chamber”, and “engine speed” means “the speed of the internal combustion engine 10”.

  In the present embodiment (hereinafter referred to as “first embodiment”), the throttle valve opening and the EGR control valve opening that can achieve the optimum intake air amount and EGR rate in accordance with the engine operating state are experimentally determined. The throttle valve opening and the EGR control valve opening determined in advance are obtained as shown in FIG. 2 (A) and FIG. 2 (B), respectively, and the target throttle valve opening TXth and the target EGR control valve are obtained. The opening degree TXegr is stored in the electronic control unit in the form of a function map of the engine speed NE and the charging efficiency KL. Then, based on the engine speed NE and the charging efficiency KL when the engine operating state is the normal operating state, the target throttle valve opening TXth and the target EGR control valve are calculated from the maps of FIGS. 2 (A) and 2 (B). Each opening degree TXegr is acquired. The operation amount to be input to the throttle valve and the EGR control valve in order to control the throttle valve opening and the EGR control valve opening to the acquired target throttle valve opening TXth and target EGR control valve opening TXegr is It is calculated as the target throttle valve operation amount and the target EGR control valve operation amount. The calculated target throttle valve operation amount and target EGR control valve operation amount are input from the electronic control unit to the throttle valve and the EGR control valve, respectively.

  Thus, the throttle valve opening is controlled to the target throttle valve opening and the EGR control valve opening is controlled to the target EGR control valve opening, whereby the target intake air amount and the target EGR rate are achieved. .

  Next, control of the throttle valve and the EGR control valve during the deceleration period will be described with reference to FIG. The “deceleration period” means “a period during which the engine operation state is in the deceleration operation state”.

  Further, in the following explanation, the “deceleration request occurrence time” means “the accelerator pedal opening decreases relatively large (especially, the accelerator pedal opening becomes zero), thereby changing the engine operation state from the normal operation state. "Minimum throttle valve opening" means "minimum opening that the throttle valve can take as its opening" and "minimum EGR control valve" “Opening” means “minimum opening that the EGR control valve can take as its opening”, “throttle valve closing speed” means “speed at which the throttle valve closes”, and “EGR control “Valve closing speed” means “speed at which the EGR control valve closes”, and “Throttle valve closing time” means “when the throttle valve opening reaches the minimum throttle valve opening during the deceleration period” Means "EGR control valve The valve time "means" when the EGR control valve opening during the deceleration period has reached minimum EGR control valve opening ". In the first embodiment, the minimum throttle valve opening is very close to zero, and the minimum EGR control valve opening is zero.

  In FIG. 3, “T0” indicates “deceleration request generation time”, “T1” indicates “throttle valve opening starts to decrease during the deceleration period”, and “Tthc” indicates “throttle valve closing”. "Tegrc" indicates "EGR control valve closing time", "Xth (T0)" indicates "throttle valve opening when deceleration request occurs", and "Xegr (T0)" indicates "deceleration" "EGR control valve opening at the time of request generation", "XthMin" indicates "minimum throttle opening", "XegrMin" indicates "minimum EGR control valve opening", and "Lth" "Legr" indicates a "line on which the EGR control valve opening follows as time passes".

  As shown in FIG. 3, in the first embodiment, the throttle valve opening starts to decrease toward the minimum throttle valve opening XthMin at a time T1 when a predetermined time Td has elapsed from the deceleration request generation time T0. The throttle valve is controlled. On the other hand, the EGR control valve is controlled so that the EGR control valve opening degree starts to decrease toward the minimum EGR control valve opening degree XegrMin at the deceleration request generation time T0. That is, in the first embodiment, the EGR control valve opening begins to decrease at the deceleration request generation time T0, and then the throttle valve opening starts to decrease at the time T1 when the predetermined time Td has elapsed from the deceleration request generation time T0. The throttle valve opening and the EGR control valve opening reach the minimum throttle valve opening XthMin and the minimum EGR control valve opening XegrMin at the same time Tthc and Tegrc, respectively. In the first embodiment, the reason for starting to decrease the EGR control valve opening before starting to decrease the throttle valve opening during the deceleration period is as follows.

  That is, the EGR control valve closing speed is slower than the throttle valve closing speed. As described above, since the minimum throttle valve opening is very close to zero and the minimum EGR control valve opening is zero, the EGR control valve opening and the throttle valve opening at the time when the deceleration request is generated. Are equal to each other, if the reduction of the throttle valve opening and the reduction of the EGR control valve opening are started at the same time when the deceleration request is generated, it is determined whether the EGR control valve closing speed is slower than the throttle valve closing speed. However, it can be said that there is an extremely high possibility that the throttle valve opening reaches the minimum throttle valve opening before the EGR control valve opening reaches the minimum EGR control valve opening. Further, when the EGR control valve opening at the time when the deceleration request is generated is larger than the throttle valve opening, if the decrease in the throttle valve opening and the decrease in the EGR control valve opening are simultaneously started at the time when the deceleration request is generated, the EGR control is performed. The possibility that the throttle valve opening reaches the minimum throttle valve opening before the valve opening reaches the minimum EGR control valve opening is further increased. Of course, if the EGR control valve opening at the time when the deceleration request is generated is smaller than the throttle valve opening, the reduction of the throttle valve opening and the decrease of the EGR control valve opening are started at the same time when the deceleration request is generated. However, the possibility that the throttle valve opening reaches the minimum throttle valve opening before the EGR control valve opening reaches the minimum EGR control valve opening is low, but this is possible unless the possibility is zero. It can be said that the nature is relatively high.

  In any case, if a decrease in the throttle valve opening and a decrease in the EGR control valve opening are started at the same time as the deceleration request is generated, the throttle valve is not reached before the EGR control valve opening reaches the minimum EGR control valve opening. There is a high possibility that the opening will reach the minimum throttle valve opening.

  Here, if the throttle valve opening reaches the minimum throttle valve opening before the EGR control valve opening reaches the minimum EGR control valve opening, the time when the throttle valve opening reaches the minimum throttle opening. From the time until the EGR control valve opening reaches the minimum EGR control valve opening, a situation occurs in which the EGR control valve opening is relatively large even though the throttle valve opening is at the minimum throttle opening. That is, there is a situation where the amount of EGR gas is relatively large even though the amount of intake air is extremely small. In this case, the amount of EGR gas in the gas in the combustion chamber is large, and as a result, misfire may occur in the combustion chamber.

  Therefore, in the first embodiment, in order to avoid a situation in which the throttle valve opening reaches the minimum throttle valve opening before the EGR control valve opening reaches the minimum EGR control valve opening, The reduction of the EGR control valve opening is started before the reduction of the throttle valve opening is started during the deceleration period.

  In the first embodiment, the predetermined time used to determine when to start decreasing the throttle valve opening during the deceleration period is the minimum EGR control valve opening during the deceleration period. The optimum time for avoiding the situation in which the throttle valve opening reaches the minimum throttle valve opening before reaching the value is obtained in advance by experiments or the like according to the engine operating state. As shown in FIG. 4, the time is stored in the electronic control unit in the form of a function map of the engine speed NE and the charging efficiency KL as a predetermined delay time Td. Then, the predetermined delay time Td is acquired from the map of FIG. 4 based on the engine speed NE and the charging efficiency KL at the time when the deceleration request is generated, and when the acquired predetermined delay time Td has elapsed from the time when the deceleration request is generated. The throttle valve opening starts to decrease.

  Further, in the map of FIG. 4, the predetermined delay time is defined as being shorter as the engine speed NE is larger and longer as the charging efficiency is larger.

  By the way, since the exhaust gas is an inert gas, when the exhaust gas is introduced into the combustion chamber, the combustion temperature of the fuel in the combustion chamber is lowered, and thereby NOx (that is, NOx resulting from the combustion of the fuel in the combustion chamber (ie, Generation of nitrogen oxides) is suppressed. Therefore, from the viewpoint of suppressing the generation of NOx resulting from the combustion of fuel in the combustion chamber, when the engine operating state is the normal operating state, the amount of EGR gas introduced into the combustion chamber by the EGR device is as much as possible. It is desirable to increase it.

  However, in order to increase the amount of EGR gas introduced into the combustion chamber by the EGR device, it is necessary to increase the EGR control valve opening. Here, if the EGR control valve opening is large, the time required for the EGR control valve opening to reach the minimum EGR control valve opening during the deceleration period becomes long, and the EGR control valve opening becomes the minimum EGR control valve opening. There is a high possibility that the throttle valve opening will reach the minimum throttle valve opening before the degree is reached.

  For this reason, it is desirable to increase the amount of EGR gas introduced into the combustion chamber by the EGR device as much as possible when the engine operation state is the normal operation state. When the engine operating state is in the normal operating state from the viewpoint of reliably suppressing the situation in which the throttle valve opening reaches the minimum throttle valve opening before the engine reaches the minimum EGR control valve opening The target EGR control valve opening is set to a value that is smaller than the normally employable opening.

  However, if the throttle valve opening does not reach the minimum throttle valve opening before the EGR control valve opening reaches the minimum EGR control valve opening during the deceleration period, the engine operating state is normal. It is preferable to increase the target EGR control valve opening degree in the operating state and increase the amount of EGR gas. Therefore, in the first embodiment, the target EGR control valve opening is increased when a specific condition is satisfied.

  Next, an increase in the target EGR control valve opening according to the first embodiment will be described with reference to FIG. 5 indicate the same parameters as the corresponding reference symbols in FIG.

  In the first embodiment, the EGR control valve closing time Tegrc and the throttle valve closing time Tthc are acquired during the deceleration period. Here, as shown in FIG. 5, during the deceleration period, the throttle valve opening changes along the solid line Lth and the EGR control valve opening changes along the chain line Legr. When the valve time Tegrc is earlier than the throttle valve closing time Tthc, the target EGR control valve opening is increased in a range in which the EGR control valve closing time is not later than the throttle valve closing time during the deceleration period.

  Thus, if the target EGR control valve opening is increased according to the first embodiment, the EGR control valve opening is reduced to the minimum EGR control valve opening when the throttle valve opening reaches the minimum throttle valve opening during the deceleration period. The effect that the amount of EGR gas introduced into the intake passage by the EGR device when the engine operating state is in the normal operating state can be increased as much as possible while suppressing the occurrence of a situation that has not reached the normal level Is obtained.

  That is, when the target EGR control valve opening is increased according to the first embodiment, naturally, the target EGR control valve opening when the engine operating state is in the normal operating state increases, and as a result, the EGR device As a result, the amount of EGR gas introduced into the intake passage increases.

  On the other hand, even if the target EGR control valve opening is increased according to the first embodiment, the target EGR control valve opening is increased within a range in which the EGR control valve closing time is not later than the throttle valve closing time during the deceleration period. Therefore, the EGR control valve opening at the time when the next deceleration request is generated becomes an opening Xegrnew that is larger than the EGR control valve opening Xegr (T0) at the time when the current deceleration request is generated. 5, the opening degree of the EGR control valve decreases along the chain line Legrnew, and the time point when the EGR control valve is closed is a time point Tegrnew that is earlier than the time point when the throttle valve is closed, or the time point when the throttle valve is closed.

  For this reason, if the target EGR control valve opening is increased according to the first embodiment, the EGR control valve opening becomes the minimum EGR control valve when the throttle valve opening reaches the minimum throttle valve opening during the deceleration period. The amount of EGR gas introduced into the intake passage by the EGR device when the engine operating state is in the normal operating state can be increased as much as possible while suppressing the situation where the opening degree has not been reached. The effect is obtained.

  When the target EGR control valve opening is increased according to the first embodiment, the EGR control valve closing time coincides with the throttle valve closing time during the deceleration period due to one increase of the target EGR control valve opening. The target EGR control valve opening degree may be increased as described above, or the target EGR control valve opening degree is increased relatively small by increasing the target EGR control valve opening degree once, so that the target EGR control valve opening degree is made a plurality of times. As a result, the target EGR control valve opening may be increased so that the EGR control valve closing time coincides with the throttle valve closing time during the deceleration period.

  Further, in the first embodiment, as described above, the deceleration operation state means that “the accelerator pedal opening is relatively reduced (particularly, the accelerator pedal opening becomes zero) and the torque required for the internal combustion engine is reduced. It means “the operating state of the internal combustion engine when it is relatively reduced”. Therefore, in the first embodiment, the target EGR control valve opening is increased when the deceleration required for the internal combustion engine is relatively large. However, the target EGR control valve opening degree may be increased when the deceleration required for the internal combustion engine is not relatively large, that is, when the deceleration is required for the internal combustion engine.

  Further, if the target EGR control valve opening is increased according to the first embodiment, in addition to the above-described effects, it is possible to suppress an unnecessarily large torque from being output from the internal combustion engine during the deceleration period, or The effect that it can suppress that fuel is consumed unnecessarily is acquired.

  That is, if the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the EGR gas amount becomes zero before the throttle valve opening reaches the minimum throttle valve opening. The intake air amount until the valve opening reaches the minimum throttle valve opening increases. Here, in general and also in the first embodiment, the amount of fuel injected from the fuel injection valve (hereinafter referred to as “fuel injection amount”) is determined in accordance with the intake air amount. As the amount of air increases, the amount of fuel injection increases. In this case, an unnecessarily large torque is output from the internal combustion engine, and fuel is unnecessarily consumed.

  However, if the target EGR control valve opening is increased according to the first embodiment, at least finally, the EGR control valve closing time coincides with the throttle valve closing time during the deceleration period.

  For this reason, if the target EGR control valve opening is increased in accordance with the first embodiment, in addition to the effects described above, it is possible to suppress the output of an unnecessarily large torque from the internal combustion engine during the deceleration period. The effect that the effect that it is possible or can suppress that fuel is consumed unnecessarily can be obtained.

  Next, acquisition of the EGR control valve closing time point used for determining whether or not to increase the target EGR control valve opening described above will be described.

In the first embodiment, the EGR control valve closing speed is grasped in advance, and the grasped EGR control valve closing speed is stored in the electronic control device as the reference EGR control valve closing speed. The stored reference EGR control valve closing speed is represented by “Vegrr”, the deceleration request occurrence time is represented by “T0”, and the EGR control valve opening at the deceleration request occurrence time is represented by “Xegr (T0)”. When expressed, the EGR control valve closing time Tegrc is acquired according to the following equation 1.
Tegrc = T0 + Xegr (T0) / Vegrr (1)

  In addition, when acquiring the EGR control valve closing time according to the above equation 1, the EGR control valve closing time predicted when the deceleration request is generated can be acquired. In other words, when the EGR control valve closing time is acquired according to the above equation 1, the EGR control valve closing time can be predicted at the time when the deceleration request is generated.

  Further, when it is not necessary to predict the EGR control valve closing time at the time when the deceleration request is generated, or when there is a request for obtaining an extremely accurate EGR control valve closing time, the EGR control valve closing according to the above equation 1 is performed. Instead of acquiring the valve time, the time when the EGR control valve opening actually reaches the minimum EGR control valve opening may be acquired as the EGR control valve closing time.

  Next, acquisition of the throttle valve closing time point used for determining whether or not to increase the target EGR control valve opening described above will be described.

In the first embodiment, the throttle valve closing speed is grasped in advance, and the grasped throttle valve closing speed is stored in the electronic control unit as the reference throttle valve closing speed. The stored reference throttle valve closing speed is represented by “Vthr”, the deceleration request occurrence time is represented by “T0”, the predetermined delay time is represented by “Td”, and the throttle valve opening at the deceleration request occurrence time is represented. Is expressed by “Xth (T0)”, the throttle valve closing time Tthc is acquired according to the following equation 2.
Tthc = T0 + Td + Xth (T0) / Vthr (2)

  In addition, when acquiring the throttle valve closing time according to the above equation 2, it is possible to acquire the EGR control valve closing time predicted when the deceleration request is generated. In other words, when the throttle valve closing time is acquired according to the above equation 2, the EGR control valve closing time can be predicted at the time when the deceleration request is generated.

  In addition, when it is not necessary to predict the throttle valve closing time at the time when the deceleration request is generated, or when there is a request for obtaining a very accurate throttle valve closing time, Instead of acquiring, the time when the throttle valve opening actually reaches the minimum throttle valve opening may be acquired as the throttle valve closing time.

  Next, the update of the reference EGR control valve closing speed used in the above equation 1 will be described.

  In order to obtain an accurate EGR control valve closing time according to the above formula 1, it is necessary that the reference EGR control valve closing speed matches the actual EGR control valve closing speed. However, when the EGR device is used for a long period of time, the EGR control valve closing speed may be slowed down, or the EGR control valve closing speed may be fastened due to a special situation. Therefore, in order to obtain an accurate EGR control valve closing time according to the above equation 1, even when the EGR control valve closing speed becomes slow or fast, the actual EGR control valve closing speed is set to A new matching reference EGR control valve closing speed should be obtained and the reference EGR control valve closing speed stored in the electronic control unit should be updated to this newly obtained reference EGR control valve closing speed. .

Therefore, in the first embodiment, when the EGR control valve opening reaches the minimum EGR control valve opening during the deceleration period, that time is acquired as the actual EGR control valve closing time. The obtained actual EGR control valve closing time is represented by “Tegrcm”, the current deceleration request occurrence time is represented by “T0”, and the EGR control valve opening at the current deceleration request occurrence time is represented by “Xegr ( (T0) ”, the EGR control valve closing speed Vegr is acquired according to the following equation (3). Then, the obtained EGR control valve closing speed Vegr is stored in the electronic control device as a new reference EGR control valve closing speed, whereby the reference EGR control valve closing speed Vegrr is updated.
Vegr = Xegr (T0) / (Tegrcm−T0) (3)

  Thus, even when the actual EGR control valve closing speed becomes slower or faster due to the update of the reference EGR control valve closing speed according to the above expression 3, the accurate according to the above expression 1. The EGR control valve closing time can be acquired.

  The update of the reference EGR control valve closing speed according to the above equation 3 is performed when the current reference EGR control valve closing speed stored in the electronic control unit is newly acquired according to the above equation 3. It may always be performed regardless of whether it is slower or faster than the valve speed, or only when the current reference EGR control valve closing speed is slower or faster than the newly acquired EGR control valve closing speed. It may be broken.

  In addition, the range of the EGR control valve closing speed in which the current reference EGR control valve closing speed stored in the electronic control device can be regarded as coincident with the actual EGR control valve closing speed is newly set according to the above equation 3. The current reference EGR control valve closing speed is set based on the newly acquired EGR control valve closing speed in accordance with Equation 3 above. The reference EGR control valve closing speed may be updated only when it is slower than the lower limit value of the EGR control valve closing speed range or faster than the upper limit value of the same range. .

  Next, the update of the reference throttle valve closing speed used in the above equation 2 will be described.

  In order to obtain an accurate throttle valve closing time according to the above equation 2, it is necessary that the reference throttle valve closing speed matches the actual throttle valve closing speed. However, when the throttle valve is used for a long period of time, the throttle valve closing speed may be slowed down, or the EGR control valve closing speed may be fastened due to a special situation. Therefore, even when the throttle valve closing speed becomes slow or fast, in order to obtain an accurate throttle valve closing time according to the above equation 2, the reference matches the actual throttle valve closing speed. A new throttle valve closing speed should be obtained and the reference throttle valve closing speed stored in the electronic control unit should be updated to this newly obtained reference throttle valve closing speed.

Therefore, in the first embodiment, when the throttle valve opening reaches the minimum throttle valve opening during the deceleration period, that time is acquired as the actual throttle valve closing time. The obtained actual throttle valve closing time is represented by “Tthcm”, the current deceleration request occurrence time is represented by “T0”, and the current predetermined delay time is represented by “Td”. When the throttle valve opening at the time is represented by “Xth (T0)”, the throttle valve closing speed Vth is acquired according to the following equation 4. The obtained throttle valve closing speed Vth is stored in the electronic control unit as a new reference throttle valve closing speed, whereby the reference throttle valve closing speed Vthr is updated.
Vth = Xth (T0) / (Tthcm−T0−Td) (4)

  Thus, even when the actual throttle valve closing speed becomes slower or faster due to the update of the reference throttle valve closing speed according to the above equation 4, the accurate throttle valve according to the above equation 2 is used. The valve closing time can be acquired.

  The update of the reference throttle valve closing speed in accordance with the above equation 4 is based on the fact that the current reference throttle valve closing speed stored in the electronic control unit is newly obtained from the throttle valve closing speed newly acquired in accordance with the above equation 4. It may be performed regardless of whether it is slow or fast, or may be performed only when the current reference throttle original valve closing speed is slower or faster than the newly acquired throttle valve closing speed.

  In addition, a range of the throttle valve closing speed at which the current reference throttle valve closing speed stored in the electronic control device can be regarded as matching the actual throttle valve closing speed is newly acquired according to the above equation 4. The throttle valve closing speed is set based on the throttle valve closing speed, and the current reference throttle valve closing speed is set based on the throttle valve closing speed newly acquired according to the above equation 4. The reference throttle valve closing speed may be updated according to the above equation 4 only when it is slower than the lower limit value of the range or faster than the upper limit value of the same range.

  By the way, if the EGR control valve closing time is later than the throttle valve closing time during the deceleration period, the intake air amount becomes extremely small before the EGR control valve opening reaches the minimum EGR control valve opening. The EGR rate until the EGR control valve opening reaches the minimum EGR control valve opening becomes extremely large. In this case, since the amount of exhaust gas in the gas sucked into the combustion chamber is extremely large, there is a high possibility that misfire will occur in the combustion chamber. Therefore, when the EGR control valve closing time during the deceleration period is later than the throttle valve closing time, it is preferable to make the throttle valve closing time coincide with the EGR control valve closing time at the EGR control valve closing time. .

  Therefore, in the first embodiment, when the EGR control valve closing time is later than the throttle valve closing time during the deceleration period, the throttle valve closing time is set so that the throttle valve closing time coincides with the EGR control valve closing time. I try to control the speed. Specifically, the throttle valve closing speed is made slow so that the throttle valve closing time coincides with the EGR control valve closing time.

  Next, control of the throttle valve closing speed according to the first embodiment will be described with reference to FIG. 6 denote the same parameters as the corresponding reference symbols in FIG.

  In the first embodiment, as shown in FIG. 6, during the deceleration period, the throttle valve opening changes along the solid line Lth and the EGR control valve opening changes along the chain line Legr. When the control valve closing time Tegrc is later than the throttle valve closing time Tthc, the throttle valve closing speed is made slow so that the throttle valve closing time Tthc coincides with the EGR control valve closing time Tegrc.

  According to this, the throttle valve opening decreases along the chain line Lthnew during the next deceleration period, and the throttle valve closing time Tthc coincides with the EGR control valve closing time Tegr.

  As described above, if the throttle valve closing speed is slowed according to the first embodiment, the throttle valve opening is reduced when the EGR control valve opening reaches the minimum EGR control valve opening during the deceleration period. It is suppressed that the situation which has not reached the degree occurs.

  The control of the throttle valve closing speed described above may always be performed regardless of the EGR rate at the time of closing the throttle valve, or the EGR rate at the time of closing the throttle valve is the allowable upper limit value (for example, the combustion chamber May be performed only when the EGR rate is larger than the upper limit value of the EGR rate at which no misfire occurs.

  As described above, when the throttle valve closing speed is controlled only when the EGR rate at the time of closing the throttle valve is larger than the allowable upper limit value, the EGR rate at the time of closing the throttle valve is For example, a physical model relating to the flow rate of air passing through a throttle valve (for example, a mass conservation law or an energy conservation law regarding air in the intake passage upstream of the throttle valve and air in the intake passage downstream of the throttle valve) (Physical model derived from the above), the amount of air passing through the throttle valve (that is, the intake air amount) is calculated, and the physical model relating to the flow rate of exhaust gas passing through the EGR control valve (for example, upstream of the EGR control valve) Mass conservation laws and energy related to the exhaust gas in the EGR passage and the exhaust gas in the EGR passage downstream of the EGR control valve The amount of exhaust gas passing through the EGR control valve from the physical model) derived from formic conservation law (i.e., to calculate the amount of EGR gas), only to be determined from these calculated intake air amount and the EGR gas amount.

  Note that when the EGR rate is obtained based on the physical model as described above, it is caused by an excessive decrease in intake pressure that may occur when the engine operating state is in a decelerating operation state or a rapid change in the surrounding environment of the internal combustion engine. Intake pressure that can be taken into account possible drastic reductions in the temperature and intake pressure of the air sucked into the combustion chamber due to a sudden change in the surrounding environment of the internal combustion engine due to a significant decrease in the outside air temperature or atmospheric pressure It is preferable to obtain the EGR rate by using the lowest intake pressure and the lowest possible air temperature.

  It was also found that the EGR control valve closing time was later than the throttle valve closing time before the throttle valve opening reached the minimum throttle valve opening during the deceleration period, and the throttle valve opening was minimized during the deceleration period. If it is possible to slow down the throttle valve closing speed before reaching the throttle valve opening, the throttle is determined when the EGR control valve closing time is later than the throttle valve closing time during the deceleration period. You may make it perform control which makes valve closing speed slow.

  Further, the lower limit of the throttle valve closing speed (for example, the throttle valve closing speed set from the viewpoint of rapidly reducing the torque output from the internal combustion engine by rapidly reducing the intake air amount during the deceleration period). When the lower limit value is set, the throttle valve closing speed during the deceleration period may be slower than the allowable lower limit value due to the control of the throttle valve closing speed described above. In this case, even when the EGR control valve closing time is later than the throttle valve closing time, the throttle valve closing speed may not be controlled.

  Further, as described above, in the first embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the target EGR control valve opening is increased. However, an allowable upper limit value for the target EGR control valve opening degree (for example, an EGR control valve opening degree value corresponding to the upper limit value of the EGR rate at which the desired internal combustion engine characteristics can be obtained when the engine operation state is in the normal operation state). When the target EGR control valve opening is increased as described above, the increased target EGR control valve opening may be larger than the allowable upper limit value. . In this case, even when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the target EGR control valve opening may not be increased.

  Further, when the target EGR control valve opening degree is not increased in this way, if the throttle valve closing speed can be increased, or by reducing the intake air amount quickly during the deceleration period. From the standpoint of rapidly reducing the torque output from the internal combustion engine, it is preferable to increase the throttle valve closing speed, and if the throttle valve closing speed can be increased, the throttle valve closing time is determined as the EGR control valve. The throttle valve closing speed may be increased within a range not earlier than the valve closing time (for example, the throttle valve closing time coincides with the EGR control valve closing time). According to this, it is possible to suppress a situation in which the throttle valve opening does not reach the minimum throttle valve opening when the EGR control valve opening reaches the minimum EGR control valve opening during the deceleration period.

  Further, as described above, in the first embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the target EGR control valve opening is increased. However, at this time, it is preferable to increase the throttle valve closing speed from the viewpoint of rapidly decreasing the torque output from the internal combustion engine by rapidly decreasing the intake air amount during the deceleration period, and the throttle valve closing speed. If the target EGR control valve opening is increased within a range where the EGR control valve closing time does not become slower than the throttle valve closing time, the throttle valve closing speed should be increased. It may be.

  As described above, in the first embodiment, when the EGR control valve closing time is later than the throttle valve closing time during the deceleration period, the throttle valve closing speed is reduced. However, instead of or in accordance with this, the predetermined delay period may be lengthened so that the throttle valve closing time coincides with the EGR control valve closing time. In particular, when the throttle valve closing time cannot be made coincident with the EGR control valve closing time only by reducing the throttle valve closing speed, the throttle valve closing time is adjusted in accordance with the slowing down of the throttle valve closing speed. The predetermined delay period may be lengthened so as to coincide with the EGR control valve closing time. In particular, when the throttle valve closing speed cannot be slowed down or when it is not preferable to slow down the throttle valve closing speed, the throttle valve closing speed is replaced with the throttle valve closing speed instead of slowing down. The predetermined delay period may be extended so that the time coincides with the EGR control valve closing time.

  Further, as described above, in the first embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the target EGR control valve opening is increased. However, in accordance with this, the predetermined delay period may be shortened so that the throttle valve closing time coincides with the EGR control valve closing time. In particular, when the EGR control valve closing time cannot be made coincident with the throttle valve closing time simply by increasing the target EGR control valve opening, the throttle valve closing is performed in accordance with the increase of the target EGR control valve opening. The predetermined delay period may be shortened so that the valve timing coincides with the EGR control valve closing timing.

  Further, as described above, when the allowable upper limit value is set for the target EGR control valve opening, when the target EGR control valve opening is increased, the increased target EGR control valve opening becomes the allowable value. When it becomes larger than the upper limit value, the target EGR control valve opening is not increased, and the predetermined delay period is shortened so that the throttle valve closing time coincides with the EGR control valve closing time. May be.

  Further, in the first embodiment, when the engine operating state is the normal operating state, the target throttle valve opening degree is determined from the maps of FIGS. 2 (A) and 2 (B) based on the engine speed NE and the charging efficiency KL. TXth and target EGR control valve opening degree TXegr are respectively acquired. However, instead of this, the target throttle valve opening TXth and the target EGR control valve opening TXegr may be set as follows.

  That is, the optimum intake air amount and EGR rate are obtained in advance by experiments or the like according to the engine operating state, and these obtained intake air amount and EGR rate are shown in FIG. 7 (A) and FIG. 7 (B). As shown, the target intake air amount TGa and the target EGR rate TRegr are stored in the electronic control unit in the form of a function map of the engine speed NE and the charging efficiency KL. When the engine operating state is the normal operating state, the target intake air amount TGa and the target EGR rate TRegr are obtained from the maps of FIGS. 7A and 7B based on the engine speed NE and the charging efficiency KL. Each is acquired. Then, by converting the acquired target intake air amount TGa and the target EGR rate TRegr according to a certain conversion law, the target intake air amount and the target EGR rate can be achieved, and the throttle valve opening and the EGR control valve opening are achieved. The degree is calculated. Then, the calculated throttle valve opening and EGR control valve opening are set to the target throttle valve opening and the target EGR control valve opening, respectively.

  When the target throttle valve opening and the target EGR control valve opening are set based on the target intake air amount and the target EGR rate acquired from FIGS. 7 (A) and 7 (B) as described above, Instead of increasing the target EGR control valve opening, the target EGR rate is increased.

  Specifically, when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the EGR control valve closing time is not delayed after the throttle valve closing time during the deceleration period. The target EGR rate is increased.

  In view of the above, the control device for the internal combustion engine of the first embodiment is widely used by introducing the exhaust gas exhausted from the combustion chamber to the throttle valve disposed in the intake passage and the exhaust passage into the intake passage. An EGR device that introduces gas into the combustion chamber, and the EGR device has an EGR control valve that controls the amount of exhaust gas introduced into the intake passage, and the engine operating state is a deceleration operation When in a normal operation state other than the state, the target intake air amount is set and the target EGR rate is set (this target EGR rate setting includes setting of the target EGR gas amount) and these are set. The throttle valve opening and the EGR control valve opening that can achieve the target intake air amount and the target EGR rate are set as the target throttle valve opening and the target EGR control valve opening, respectively. The throttle valve and the EGR control valve are controlled in accordance with the set target throttle valve opening and the target EGR control valve opening, respectively. When a deceleration request for the internal combustion engine is generated, the throttle valve opening is set to the minimum throttle valve opening. And the EGR control valve opening is decreased to the minimum EGR control valve opening, and when the EGR control valve closing time is earlier than the throttle valve closing time after the deceleration request of the internal combustion engine is generated, the EGR control valve Target EGR control set as an EGR control valve opening that can achieve the target EGR rate that is set when the engine operating state is in the normal operating state within a range in which the valve closing time is not later than the throttle valve closing time. A control device that increases the valve opening or increases the target EGR rate that is set when the engine operating state is in a normal operating state. Obtain.

  Next, an example of a routine for executing control of the throttle valve and the EGR control valve according to the first embodiment will be described. This routine is shown in FIG. 8, and is executed at predetermined time intervals during engine operation.

  When the routine of FIG. 8 is started, first, at step 10, the current engine speed NE, the current charging efficiency KL, and the current accelerator pedal opening decrease rate Ps are acquired. Next, at step 11, whether or not the current accelerator pedal opening decrease rate Ps acquired at step 10 is larger than a predetermined decrease rate Psth (Ps> Psth), that is, whether a deceleration request has occurred. Is determined. Here, when it is determined that Ps> Psth, the routine proceeds to step 12. On the other hand, when it is determined that Ps ≦ Psth, the routine proceeds to step 18.

  When it is determined in step 11 that Ps> Psth (that is, it is determined that a deceleration request has occurred) and the routine proceeds to step 12, the current engine speed NE acquired in step 10 and the current charging are acquired. Based on the efficiency KL, the predetermined delay period Td is acquired from the map of FIG. Next, at step 13, the target throttle valve opening TXth is set to the minimum throttle valve opening XthMin, and the target EGR control valve opening TXegr is set to the minimum EGR control valve opening XegrMin. Next, at step 14, the target throttle valve opening TXth (that is, the minimum throttle valve opening XthMin) and the target EGR control valve opening TXegr (that is, the minimum EGR control valve opening XegrMin) set at step 13 are achieved. A target throttle valve operation amount Mth and a target EGR control valve operation amount Megr that can be calculated are calculated. Next, at step 15, the target EGR control valve operation amount Megr calculated at step 14 is input to the EGR control valve. As a result, the EGR control valve opening begins to decrease toward the minimum EGR control valve opening.

  Next, at step 16, whether or not the current time T exceeds the time when the predetermined delay time Td acquired at step 12 has elapsed from the time T0 when the deceleration request is generated (T ≧ T0 + Td), that is, the deceleration request. It is determined whether or not a predetermined delay time has elapsed since the occurrence of this. Here, when it is determined that T ≧ T0 + Td, the routine proceeds to step 17. On the other hand, when it is determined that T <T0 + Td, the routine repeats step 16. That is, the routine repeats step 16 until it is determined in step 16 that T ≧ T0 + Td.

  When it is determined in step 16 that T ≧ T0 + Td and the routine proceeds to step 17, the target throttle valve operation amount Mth calculated in step 14 is input to the throttle valve, and the routine ends. As a result, the throttle valve opening begins to decrease toward the minimum throttle valve opening.

  On the other hand, if it is determined in step 11 that Ps ≦ Psth (that is, it is determined that no deceleration request has been generated and the engine operating state is in the normal operating state), and the routine proceeds to step 18, Based on the acquired engine speed NE and charging efficiency KL, the target throttle valve opening TXth and the target EGR control valve opening TXegr are acquired from the maps of FIGS. 2 (A) and 2 (B). Next, in step 19, the target throttle valve operation amount Mth and the target EGR control valve operation amount Megr that can achieve the target throttle valve opening TXth and the target EGR control valve opening TXegr acquired in step 18 are calculated. Is done. Next, at step 20, the target throttle valve operation amount Mth calculated at step 19 is input to the throttle valve, and the target EGR control valve operation amount Megr calculated at step 19 is input to the EGR control valve. finish. As a result, the throttle valve opening and the EGR control valve opening start to change toward the target throttle valve opening and the target EGR control valve opening, respectively.

  Next, an example of a routine for executing an increase in the target EGR control valve opening according to the first embodiment will be described. This routine is shown in FIGS. 9 to 12, and is executed at predetermined time intervals during engine operation.

  When the routines of FIGS. 9 to 12 are started, first, at step 100, the current reduction rate Ps of the accelerator pedal opening is acquired. Next, at step 101, whether or not the current accelerator pedal opening decrease rate Ps acquired at step 100 is larger than a predetermined decrease rate Psth (Ps> Psth), that is, whether or not a deceleration request is generated. Is determined. If it is determined that Ps> Psth, the routine proceeds to step 102. On the other hand, when it is determined that Ps ≧ Psth, the routine ends as it is.

  If it is determined in step 101 that Ps> Psth, and the routine proceeds to step 102, the current engine speed NE, the current charging efficiency KL, the deceleration request generation time T0, and the throttle valve opening Xth ( T0), the EGR control valve opening Xegr (T0) at the time when the deceleration request is generated, the current reference throttle valve closing speed Vthr, and the current reference EGR control valve closing speed Vegrr. Next, at step 103, a predetermined delay period Td is acquired from the map of FIG. 4 based on the current engine speed NE acquired at step 102 and the current charging efficiency KL.

  Next, at step 104, the deceleration request generation time T0 acquired at step 102, the throttle valve opening Xth (T0) at the time of the deceleration request generation, the current reference throttle valve closing speed Vthr, and the predetermined delay acquired at step 103. The throttle valve closing time Tthc is calculated from the above equation 2 using the time Td, the deceleration request generation time T0 acquired in step 102, the EGR control valve opening Xegr (T0) at the time when the deceleration request is generated, and the current time The EGR control valve closing time Tegrc is calculated from the above equation 1 using the reference EGR control valve closing speed Vegrr.

  Next, at step 105, whether or not the EGR control valve closing time Tegrc calculated at step 104 is smaller than the throttle valve closing time Tthc calculated at step 104 (Tegrc <Tthc), that is, the EGR control valve closing. It is determined whether or not the valve timing is earlier than the throttle valve closing timing. Here, when it is determined that Tegrc <Tthc, the routine proceeds to step 106. On the other hand, when it is determined that Tegrc ≧ Tthc, the routine proceeds to step 118 in FIG.

  In step 105, it is determined that Tegrc <Tthc (that is, it is determined that the EGR control valve closing time is earlier than the throttle valve closing time), and when the routine proceeds to step 106, the actual throttle valve closing time Tthcm And the actual EGR control valve closing time Tegrcm are obtained.

  Next, at step 107, the deceleration request generation time T0 acquired at step 102, the throttle valve opening Xth (T0) at the time of the deceleration request generation, the predetermined delay time Td acquired at step 103, and the actual acquired at step 106 The throttle valve closing speed Vthm is calculated from the above equation 4 using the throttle valve closing time Tthcm of the throttle valve, and the EGR control valve opening Xegr at the deceleration request generation time T0 and the deceleration request generation time acquired in step 102 is calculated. The EGR control valve closing speed Vegrm is calculated from the above equation 3 using (T0) and the actual EGR control valve closing time Tegrcm acquired in step 106.

  Next, in step 108 of FIG. 10, the current reference EGR control valve closing speed Vegrr acquired in step 102 is within a predetermined range with respect to the EGR control valve closing speed Vegrm calculated in step 107 (Vegrm It is determined whether or not −Kegr ≦ Vegrr ≦ Vegrm + Kegr). If it is determined that Vegrm−Kegr ≦ Vegrr ≦ Vegrm + Kegr, the routine proceeds to step 109. On the other hand, if it is determined that Vegrm−Kegr ≦ Vegrr ≦ Vegrm + Kegr, the routine proceeds to step 113.

  In step 108, it is determined that Vegrm−Kegr ≦ Vegrr ≦ Vegrm + Kegr (that is, it is determined that the current reference EGR control valve closing speed is within a predetermined range with respect to the actual EGR control valve closing speed). When the routine proceeds to step 109, the current reference throttle valve closing speed Vthr acquired in step 102 is within a predetermined range with respect to the throttle valve closing speed Vthm calculated in step 107 (Vthm−Kth ≦ It is determined whether or not Vthr ≦ Vthm + Kth). Here, if it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 110. On the other hand, if it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 111.

  In step 109, it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is within a predetermined range with respect to the actual throttle valve closing speed), and the routine is executed. When the routine proceeds to step 110, it can be said that the reference EGR control valve closing speed is substantially equal to the actual EGR control valve closing speed and the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. It is not necessary to update the EGR control valve closing speed and the reference throttle valve closing speed, and the target EGR control valve opening degree can be increased because the EGR control valve closing time is earlier than the throttle valve closing time. In step 110, the target EGR control valve opening TXegr is increased, and the routine ends. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  On the other hand, it is determined in step 109 that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is not within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 111, it can be said that the reference EGR control valve closing speed is substantially equal to the actual EGR control valve closing speed, but the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. Since it is not possible to update the reference EGR control valve closing speed, it is necessary to update the reference throttle valve closing speed, and the EGR control valve closing time is earlier than the throttle valve closing time. Since it is allowed to increase the target EGR control valve opening, in step 111, the target EGR control valve opening TXegr is increased. Is, then, in step 112, the current reference throttle valve closing speed Vthr updated on the throttle valve closing speed Vthm calculated in step 107, the routine is terminated. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  On the other hand, it is determined in step 108 that Vegrm−Kegr ≦ Vegr ≦ Vegrm + Kegr is not satisfied (that is, it is determined that the current reference EGR control valve closing speed is not within a predetermined range with respect to the actual EGR control valve closing speed). When the routine proceeds to step 113, the current reference throttle valve closing speed Vthr acquired at step 102 is within a predetermined range with respect to the throttle valve closing speed Vthm calculated at step 107 (Vthm− It is determined whether or not Kth ≦ Vthr ≦ Vthm + Kth). Here, if it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 114. On the other hand, if it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 116.

  In step 113, it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is within a predetermined range with respect to the actual throttle valve closing speed), and the routine is executed. When the routine proceeds to step 114, it can be said that the reference EGR control valve closing speed is not substantially equal to the actual EGR control valve closing speed, but the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. Therefore, it is necessary to update the reference EGR control valve closing speed, but it is not necessary to update the reference throttle valve closing speed, and since the EGR control valve closing time is earlier than the throttle valve closing time, the target EGR Since it is allowed to increase the control valve opening, in step 114, the target EGR control valve opening TXegr is increased, Ide, in step 115, the current reference EGR control valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 107, the routine is terminated. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  On the other hand, it is determined in step 113 that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is not within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 116, it cannot be said that the reference EGR control valve closing speed is substantially equal to the actual EGR control valve closing speed, and the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. Therefore, it is necessary to update both the reference EGR control valve closing speed and the reference throttle valve closing speed, and since the EGR control valve closing time is earlier than the throttle valve closing time, the target EGR control valve opening In step 116, the target EGR control valve opening TXegr is increased, and then the step is allowed. In step 117, the current reference throttle valve closing speed Vthr is updated to the throttle valve closing speed Vthm calculated in step 107, and the current reference EGR control valve closing speed Vegrr is calculated in step 107. The control valve closing speed Vegrm is updated, and the routine ends. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  On the other hand, when it is determined in step 105 in FIG. 9 that Tegrc ≧ Tthc and the routine proceeds to step 118 in FIG. 11, the EGR control valve closing time Tegrc calculated in step 104 is the throttle valve calculated in step 104. It is determined whether or not the valve closing time Tthc is larger (Tegrc> Tthc), that is, whether or not the EGR control valve closing time is later than the throttle valve closing time. Here, if it is determined that Tegrc> Tthc, the routine proceeds to step 119. On the other hand, when it is determined that Tegrc ≦ Tthc, the routine ends as it is.

  In step 118, it is determined that Tegrc> Tthc (that is, it is determined that the EGR control valve closing time is later than the throttle valve closing time), and when the routine proceeds to step 119, the actual condition at the throttle valve closing time Tthc is reached. The EGR rate Regr (Tthc) of is acquired. Next, at step 120, whether or not the EGR rate Regr (Tthc) acquired at step 119 is larger than its allowable upper limit value (for example, the upper limit value of the EGR rate at which misfire does not occur in the combustion chamber) Cegr (Regr> Cegr). Is determined. Here, if it is determined that Regr> Cegr, the routine proceeds to step 121. On the other hand, when it is determined that Regr ≦ Cegr, the routine ends as it is. That is, when Regr ≦ Cegr, the actual EGR rate at the time of closing the throttle valve is equal to or lower than the allowable upper limit value, and therefore, the possibility of misfire in the combustion chamber at the time of closing the throttle valve is extremely low. It is determined that it is acceptable that the EGR control valve closing time is later than the throttle valve closing time, and the routine is terminated without slowing down the throttle valve closing speed.

  When it is determined in step 120 that Regr> Cegr and the routine proceeds to step 121, the actual throttle valve closing time Tthcm and the actual EGR control valve closing time Tegrcm are acquired. Next, at step 122, the deceleration request generation time T0 acquired at step 102, the throttle valve opening Xth (T0) at the time of the deceleration request generation, the predetermined delay time Td acquired at step 103, and the actual acquired at step 121. The throttle valve closing speed Vthm is calculated from the above equation 4 using the throttle valve closing time Tthcm of the throttle valve, and the EGR control valve opening Xegr at the deceleration request generation time T0 and the deceleration request generation time acquired in step 102 is calculated. The EGR control valve closing speed Vegrm is calculated from the above equation 3 using (T0) and the actual EGR control valve closing time Tegrcm acquired in step 121.

  Next, in step 123 of FIG. 12, the current reference EGR control valve closing speed Vegrr acquired in step 102 is within a predetermined range with respect to the EGR control valve closing speed Vegrm calculated in step 122 (Vegrm It is determined whether or not −Kegr ≦ Vegrr ≦ Vegrm + Kegr). Here, if it is determined that Vegrm−Kegr ≦ Vegrr ≦ Vegrm + Kegr, the routine proceeds to step 124. On the other hand, if it is determined that Vegrm−Kegr ≦ Vegrr ≦ Vegrm + Kegr, the routine proceeds to step 128.

  In step 123, it is determined that Vegrm−Kegr ≦ Vegrr ≦ Vegrm + Kegr (that is, it is determined that the current reference EGR control valve closing speed is within a predetermined range with respect to the actual EGR control valve closing speed). When the routine proceeds to step 124, the current reference throttle valve closing speed Vthr acquired in step 102 is within a predetermined range with respect to the throttle valve closing speed Vthm calculated in step 122 (Vthm−Kth ≦ It is determined whether or not Vthr ≦ Vthm + Kth). When it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 125. On the other hand, if it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 126.

  In step 124, it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is within a predetermined range with respect to the actual throttle valve closing speed), and the routine is executed. When the routine proceeds to step 125, it can be said that the reference EGR control valve closing speed is substantially equal to the actual EGR control valve closing speed and the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. It is not necessary to update the EGR control valve closing speed and the reference throttle valve closing speed, and it is preferable to slow down the throttle valve closing speed because the EGR control valve closing time is later than the throttle valve closing time. Therefore, in step 125, the throttle valve closing speed Vth is decreased, and the routine ends. In this case, during the next deceleration period, the throttle valve opening is reduced by the throttle valve closing speed slowed in step 125.

  On the other hand, it is determined in step 124 that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is not within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 126, it can be said that the reference EGR control valve closing speed is substantially equal to the actual EGR control valve closing speed, but the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. Since it is not possible to update the reference EGR control valve closing speed, it is necessary to update the reference throttle valve closing speed, and the EGR control valve closing time is later than the throttle valve closing time. Since it is preferable to slow down the throttle valve closing speed, in step 126, the throttle valve closing speed Vth is decreased, Ide, in step 127, the current reference throttle valve closing speed Vthr is updated to a throttle valve closing speed Vthm calculated in step 122, the routine is terminated. In this case, during the next deceleration period, the throttle valve opening is reduced by the throttle valve closing speed slowed in step 126.

  On the other hand, in step 123, it is determined that Vegrm−Kegr ≦ Vegrr ≦ Vegrm + Kegr is not satisfied (that is, it is determined that the current reference EGR control valve closing speed is not within a predetermined range with respect to the actual EGR control valve closing speed). When the routine proceeds to step 128, the current reference throttle valve closing speed Vthr acquired at step 102 is within a predetermined range with respect to the throttle valve closing speed Vthm calculated at step 122 (Vthm− It is determined whether or not Kth ≦ Vthr ≦ Vthm + Kth). When it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 129. On the other hand, if it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth, the routine proceeds to step 131.

  In step 128, it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is within a predetermined range with respect to the actual throttle valve closing speed), and the routine is executed. When the routine proceeds to step 129, it can be said that the reference EGR control valve closing speed is not substantially equal to the actual EGR control valve closing speed, but the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. Therefore, it is necessary to update the reference EGR control valve closing speed, but it is not necessary to update the reference throttle valve closing speed, and the EGR control valve closing time is later than the throttle valve closing time. Since it is preferable to reduce the valve closing speed, in step 129, the throttle valve closing speed Vth is decreased, and then In step 130, the current reference EGR control valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 122, the routine is terminated. Note that in this case, during the next deceleration period, the throttle valve opening is reduced by the throttle valve closing speed delayed in step 129.

  On the other hand, it is determined in step 128 that Vthm−Kth ≦ Vthr ≦ Vthm + Kth is not satisfied (that is, it is determined that the current reference throttle valve closing speed is not within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 131, the reference EGR control valve closing speed cannot be said to be substantially equal to the actual EGR control valve closing speed, and the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. Therefore, it is necessary to update both the reference EGR control valve closing speed and the reference throttle valve closing speed, and the EGR control valve closing time is later than the throttle valve closing time. In step 131, the throttle valve closing speed Vth is decreased. 2, the current reference throttle valve closing speed Vthr is updated to the throttle valve closing speed Vthm calculated in step 122, and the current reference EGR control valve closing speed Vegrr is calculated in step 122. The valve closing speed Vegrm is updated, and the routine ends. During the next deceleration period, the throttle valve opening is reduced by the throttle valve closing speed delayed in step 132.

  Next, a control device for an internal combustion engine according to a second embodiment of the present invention will be described.

  In the first embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the relationship between the reference EGR control valve closing speed at that time and the actual EGR control valve closing speed is considered. Instead, the target EGR control valve opening is increased. In contrast, in the second embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time, the target EGR control valve opening is increased as follows.

  That is, in the second embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time, the actual EGR control valve closing speed is calculated using Equation 3 above. The calculated EGR control valve closing speed is compared with the current reference EGR control valve closing speed stored in the electronic control unit, and the calculated EGR control valve closing speed is compared with the current reference EGR. When the control valve closing speed is slower, the target EGR control valve opening degree is not increased. That is, an increase in the target EGR control valve opening is prohibited. On the other hand, when the calculated EGR control valve closing speed is equal to the current EGR control valve closing speed or faster than the current EGR control valve closing speed, the target EGR control valve is the same as in the first embodiment. The opening is increased.

  Thus, even when the EGR control valve closing time is earlier than the throttle valve closing time, when the actual EGR control valve closing speed is slower than the reference EGR control valve closing speed at that time, the target EGR The reason why the control valve opening is not increased is as follows.

  That is, the fact that the actual EGR control valve closing speed is slower than the reference EGR control valve closing speed at that time means that the actual EGR control valve closing speed has become slower with the passage of time. Therefore, there is a concern that the actual EGR control valve closing speed will become slower in the future. In spite of such concerns, if the target EGR control valve opening is increased, the EGR control valve closing time in the deceleration period is actually reduced when the EGR control valve closing speed is further slowed down. There is a high possibility that a situation will occur where the throttle valve is closed later than the time when the throttle valve is closed.

  In order to avoid such a situation, even if the EGR control valve closing time is earlier than the throttle valve closing time in the deceleration period, the actual EGR control valve closing speed is the reference EGR control at that time. When the valve closing speed is slower than the valve closing speed, the target EGR control valve opening degree should not be increased.

  For these reasons, in the second embodiment, even when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the actual EGR control valve closing speed is the reference EGR control valve closing at that time. When it is slower than the valve speed, the target EGR control valve opening is not increased.

  In accordance with this, in the second embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time in the deceleration period, the actual EGR control valve closing speed is the reference EGR control valve closing time at that time. When the valve speed is equal to or faster than the reference EGR control valve closing speed at that time, the target EGR control valve opening is increased. As a result, according to the second embodiment, EGR gas amount is possible when the engine operating state is in the normal operating state while more reliably suppressing the situation in which the EGR control valve closing time is later than the throttle valve closing time during the deceleration period. The effect that can be made as much as possible is obtained.

  Note that the data used for calculating the actual EGR control valve closing speed (that is, the EGR control valve opening Xegr (T0) at the time when the deceleration request is generated, the actual EGR control valve closing time Tegrcm, and the deceleration request) Since the occurrence time T0) includes some errors, the actual EGR control valve closing speed is slower than the reference EGR control valve closing speed at that time, but very close to the reference EGR control valve closing speed at that time In this case, there is a high possibility that the actual EGR control valve closing speed is not slower than the reference EGR control valve closing speed at that time. Then, if the actual EGR control valve closing speed is not slower than the reference EGR control valve closing speed at that time, the viewpoint of increasing the EGR gas amount as much as possible when the engine operating state is in the normal operating state Therefore, it is preferable to increase the target EGR control valve opening.

  Therefore, in the second embodiment, a speed obtained by adding an appropriate value to the EGR control valve closing speed calculated using the above equation 3 (hereinafter, this speed is referred to as “corrected EGR control valve closing speed”) and the speed at that time The reference EGR control valve closing speed is compared, and when the corrected EGR control valve closing speed is slower than the reference EGR control valve closing speed, the target EGR control valve opening is not increased and the corrected EGR control valve closing speed is increased. May be equal to the reference EGR control valve closing speed or faster than the reference EGR control valve closing speed, the target EGR control valve opening may be increased.

  An example of a routine for executing control of the throttle valve and the EGR control valve according to the second embodiment is the routine of FIG.

  Next, an example of a routine for executing an increase in the target EGR control valve opening according to the second embodiment will be described. This routine is shown in FIGS. 13 to 16, and is executed at predetermined time intervals during engine operation. Steps 200 to 213 and steps 218 to 232 of the routines of FIGS. 13 to 16 are the same as steps 100 to 113 and steps 118 to 132 of the routines of FIGS. 9 to 12. Therefore, refer to the description of FIGS. 9 to 12 for these steps.

  In step 213 of FIG. 14, it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 214A, the current reference EGR control valve closing speed Vegrr acquired in step 202 is a speed that is larger than the EGR control valve closing speed Vegrm calculated in step 207 by a predetermined value (Vegrm + Kegr). Is greater than (Vegrm> Vegrm + Kegr), that is, whether the actual EGR control valve closing speed is surely slower than the current reference EGR control valve closing speed is determined. Here, when it is determined that Vegrm> Vegrm + Kegr, the routine proceeds to step 214B. On the other hand, when it is determined that Vegrm ≦ Vegrm + Kegr, the routine proceeds to step 214C.

  When it is determined in step 214A that Vegrm> Vegrm + Kegr (that is, it is determined that the actual EGR control valve closing speed is surely slower than the current reference EGR control valve closing speed), and the routine proceeds to step 214B The target EGR control valve opening should not be increased because the actual EGR control valve closing speed is surely slower than the current reference EGR control valve closing speed, but the reference EGR control valve closing speed is updated. In step 214B, it is not necessary to update the reference throttle valve closing speed because the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. The valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 207, and the routine There is terminated.

  On the other hand, in step 214A, it is determined that Vegrm ≦ Vegrm + Kegr (that is, it is determined that the actual EGR control valve closing speed is not surely slower than the current reference EGR control valve closing speed), and the routine proceeds to step 214C. When the process proceeds to step S2, the actual EGR control valve closing speed is not surely slower than the current reference EGR control valve closing speed, so that it is allowed to increase the target EGR control valve opening and the reference EGR control. Since it is necessary to update the valve closing speed, and since it can be said that the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed, there is no need to update the reference throttle valve closing speed. In step 214D, the target EGR control valve opening TXegr is increased. Valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 207, the routine is terminated. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  On the other hand, it is determined in step 213 in FIG. 14 that Vthm−Kth ≦ Vthr ≦ Vthm + Kth is not satisfied (that is, it is determined that the current reference throttle valve closing speed is not within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 215A, the current reference EGR control valve closing speed Vegrr acquired in step 202 is a speed that is larger than the EGR control valve closing speed Vegrm calculated in step 207 by a predetermined value ( It is determined whether or not it is larger than (Vegrm + Kegr) (Vegrm> Vegrm + Kegr), that is, whether or not the actual EGR control valve closing speed is surely slower than the current reference EGR control valve closing speed. Here, when it is determined that Vegrm> Vegrm + Kegr, the routine proceeds to step 215B. On the other hand, when it is determined that Vegrm ≦ Vegrm + Kegr, the routine proceeds to step 215C.

  When it is determined in step 215A that Vegrm> Vegrm + Kegr (that is, it is determined that the actual EGR control valve closing speed is surely slower than the current reference EGR control valve closing speed), and the routine proceeds to step 215B The target EGR control valve opening should not be increased because the actual EGR control valve closing speed is surely slower than the current reference EGR control valve closing speed, but the reference EGR control valve closing speed is updated. In step 215B, since the reference throttle valve closing speed is not substantially equal to the actual throttle valve closing speed, it is necessary to update the reference throttle valve closing speed. The throttle valve closing speed Vthr is updated to the throttle valve closing speed Vthm calculated in step 207, Standing reference EGR control valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 207, the routine is terminated.

  On the other hand, it is determined in step 215A that Vegrm ≦ Vegrm + Kegr (that is, it is determined that the actual EGR control valve closing speed is not surely slower than the current reference EGR control valve closing speed), and the routine is executed in step 215C. When the process proceeds to step S2, the actual EGR control valve closing speed is not surely slower than the current reference EGR control valve closing speed, so that it is allowed to increase the target EGR control valve opening and the reference EGR control. Since it is necessary to update the valve closing speed and the reference throttle valve closing speed is not substantially equal to the actual throttle valve closing speed, it is necessary to update the reference throttle valve closing speed. In step 215C, the target EGR control valve opening TXegr is increased, and then in step 215D, the current reference slot is The toll valve closing speed Vthrr is updated to the throttle valve closing speed Vthm calculated in step 207, and the current reference EGR control valve closing speed Vegrr is changed to the EGR control valve closing speed Vegrm calculated in step 207. It is updated and the routine ends. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  When it is determined in step 214A and step 215A that Vegrm> Vegrm + Kegr, the target EGR control valve opening is not increased and the reference EGR control valve closing speed and / or the reference throttle valve closing speed is updated. Done. The reason why such a correspondence is adopted when Vegrm> Vegrm + Kegr is as described above, but from another viewpoint, when Vegrm> Vegrm + Kegr, the reference EGR control valve is more than the increase in the target EGR control valve opening degree. It can be said that the priority is given to the updating of the valve closing speed and / or the reference throttle valve closing speed.

  Next, an internal combustion engine control apparatus according to a third embodiment of the present invention will be described.

  In the first embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the relationship between the reference EGR control valve closing speed at that time and the actual EGR control valve closing speed is considered. Instead, the target EGR control valve opening is increased. In contrast, in the third embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time, the target EGR control valve opening is increased as follows.

  That is, in the third embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time, the actual EGR control valve closing speed is calculated using Equation 3 above. The calculated EGR control valve closing speed is compared with the current reference EGR control valve closing speed stored in the electronic control unit, and the calculated EGR control valve closing speed is compared with the current reference EGR. When the control valve closing speed is faster, the target EGR control valve opening is not increased. That is, an increase in the target EGR control valve opening is prohibited. On the other hand, when the calculated EGR control valve closing speed is equal to the current EGR control valve closing speed or slower than the current EGR control valve closing speed, the target EGR control valve is the same as in the first embodiment. The opening is increased.

  Thus, even when the EGR control valve closing time is earlier than the throttle valve closing time, when the actual EGR control valve closing speed is faster than the reference EGR control valve closing speed at that time, the target EGR The reason why the control valve opening is not increased is as follows.

  That is, when the EGR control valve is controlled according to a certain control law, it is unlikely that the EGR control valve closing speed will gradually increase with time. Therefore, when the actual EGR control valve closing speed is faster than the reference EGR control valve closing speed at that time, the steady situation of increasing the EGR control valve closing speed is not acting on the EGR control valve. It is also considered that a sudden situation in which the EGR control valve closing speed is increased has acted on the EGR control valve. In this case, if such a sudden situation does not act on the EGR control valve again, there is a concern that the EGR control valve closing speed will not be higher than the reference EGR control valve closing speed at that time. In spite of such concerns, if the target EGR control valve opening is increased, the EGR control valve closing speed is not actually faster than the reference EGR control valve closing speed at that time. In the deceleration period, there is a high possibility that a situation will occur in which the EGR control valve closing time becomes later than the throttle valve closing time.

  In order to avoid such a situation, even if the EGR control valve closing time is earlier than the throttle valve closing time in the deceleration period, the actual EGR control valve closing speed is the reference EGR control at that time. When the valve closing speed is faster, the target EGR control valve opening degree should not be increased.

  For this reason, in the third embodiment, even when the EGR control valve closing time is earlier than the throttle valve closing time during the deceleration period, the actual EGR control valve closing speed is the reference EGR control valve closing at that time. When it is faster than the valve speed, the target EGR control valve opening is not increased.

  In accordance with this, in the third embodiment, when the EGR control valve closing time is earlier than the throttle valve closing time in the deceleration period, the actual EGR control valve closing speed is the reference EGR control valve closing time at that time. When the valve speed is equal to or slower than the reference EGR control valve closing speed at that time, the target EGR control valve opening is increased. As a result, according to the third embodiment, EGR gas amount is possible when the engine operating state is in the normal operating state while more reliably suppressing the situation in which the EGR control valve closing time is later than the throttle valve closing time during the deceleration period. The effect that can be made as much as possible is obtained.

  As described in relation to the second embodiment, data used for calculating the actual EGR control valve closing speed (that is, the EGR control valve opening Xegr (T0) at the time when the deceleration request is generated, the actual Since the EGR control valve closing time Tegrcm and the deceleration request generation time T0) include some errors, the actual EGR control valve closing speed is faster than the reference EGR control valve closing speed at that time. Is very close to the reference EGR control valve closing speed at that time, there is a high possibility that the actual EGR control valve closing speed is not faster than the reference EGR control valve closing speed at that time. Then, if the actual EGR control valve closing speed is not faster than the reference EGR control valve closing speed at that time, the viewpoint of increasing the EGR gas amount as much as possible when the engine operating state is in the normal operating state Therefore, it is preferable to increase the target EGR control valve opening.

  Therefore, in the third embodiment, a speed obtained by subtracting an appropriate value from the EGR control valve closing speed calculated by using the above equation 3 (hereinafter, this speed is referred to as “corrected EGR control valve closing speed”) and the speed at that time The reference EGR control valve closing speed is compared. When the corrected EGR control valve closing speed is faster than the reference EGR control valve closing speed, the target EGR control valve opening is not increased and the corrected EGR control valve closing speed is increased. May be equal to the reference EGR control valve closing speed or slower than the reference EGR control valve closing speed, the target EGR control valve opening may be increased.

  In the third embodiment, similarly to the second embodiment, the target EGR is also obtained when the EGR control valve closing speed calculated using the above equation 3 is slower than the current reference EGR control valve closing speed. An increase in the control valve opening degree may be prohibited.

  An example of a routine for executing control of the throttle valve and the EGR control valve according to the third embodiment is the routine of FIG.

  Next, an example of a routine for increasing the target EGR control valve opening according to the third embodiment will be described. This routine is shown in FIGS. 17 to 20, and is executed at predetermined time intervals during engine operation. Note that steps 300 to 313 and steps 318 to 332 of the routines of FIGS. 17 to 20 are the same as steps 100 to 113 and steps 118 to 132 of the routines of FIGS. 9 to 12. Therefore, refer to the description of FIGS. 9 to 12 for these steps.

  In step 313 in FIG. 18, it is determined that Vthm−Kth ≦ Vthr ≦ Vthm + Kth (that is, it is determined that the current reference throttle valve closing speed is within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 314A, the current reference EGR control valve closing speed Vegrr acquired in step 302 is smaller than the EGR control valve closing speed Vegrm calculated in step 307 by a predetermined value (Vegrm− It is determined whether or not it is smaller than (Kegr) (Vegrm <Vegrm−Kegr), that is, whether or not the actual EGR control valve closing speed is surely faster than the current reference EGR control valve closing speed. Here, when it is determined that Vegrm <Vegrm−Kegr, the routine proceeds to step 314B. On the other hand, when it is determined that Vegrm ≧ Vegrm−Kegr, the routine proceeds to step 314C.

  In step 314A, it is determined that Vegrm <Vegrm−Kegr (that is, it is determined that the actual EGR control valve closing speed is surely faster than the current reference EGR control valve closing speed), and the routine proceeds to step 314B. In this case, the target EGR control valve opening should not be increased because the actual EGR control valve closing speed is surely faster than the current reference EGR control valve closing speed, but the reference EGR control valve closing speed should be In step 314B, there is no need to update the reference throttle valve closing speed because the reference throttle valve closing speed needs to be updated, and it can be said that the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed. The EGR control valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 307, and the routine There is terminated.

  On the other hand, in step 314A, it is determined that Vegrm ≧ Vegrm−Kegr (that is, it is determined that the actual EGR control valve closing speed is not surely faster than the current reference EGR control valve closing speed), and the routine is executed. When the routine proceeds to step 314C, the actual EGR control valve closing speed is not surely higher than the current reference EGR control valve closing speed, so that it is permitted to increase the target EGR control valve opening and reference. Since it is necessary to update the EGR control valve closing speed and the reference throttle valve closing speed is substantially equal to the actual throttle valve closing speed, it is not necessary to update the reference throttle valve closing speed. In step 314C, the target EGR control valve opening TXegr is increased, and then in step 314D, the current reference EGR control value is increased. Valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 307, the routine is terminated. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  On the other hand, it is determined in step 313 in FIG. 18 that Vthm−Kth ≦ Vthr ≦ Vthm + Kth is not satisfied (that is, it is determined that the current reference throttle valve closing speed is not within a predetermined range with respect to the actual throttle valve closing speed). When the routine proceeds to step 315A, the current reference EGR control valve closing speed Vegrr acquired in step 302 is smaller than the EGR control valve closing speed Vegrm calculated in step 307 by a predetermined value ( It is determined whether or not (Vegrm <Vegrm−Kegr) is smaller than (Vegrm−Kegr), that is, whether or not the actual EGR control valve closing speed is surely faster than the current reference EGR control valve closing speed. . Here, when it is determined that Vegrm <Vegrm−Kegr, the routine proceeds to step 315B. On the other hand, when it is determined that Vegrm ≧ Vegrm + Kegr, the routine proceeds to step 315C.

  In step 315A, it is determined that Vegrm <Vegrm-Kegr (that is, it is determined that the actual EGR control valve closing speed is surely faster than the current reference EGR control valve closing speed), and the routine proceeds to step 315B. In this case, the target EGR control valve opening should not be increased because the actual EGR control valve closing speed is surely faster than the current reference EGR control valve closing speed, but the reference EGR control valve closing speed should be In step 315B, it is necessary to update the reference throttle valve closing speed because the reference throttle valve closing speed is not substantially equal to the actual throttle valve closing speed. The reference throttle valve closing speed Vthr is updated to the throttle valve closing speed Vthm calculated in step 307, Standing reference EGR control valve closing speed Vegrr is updated to the EGR control valve closing speed Vegrm calculated in step 307, the routine is terminated.

  On the other hand, in step 315A, it is determined that Vegrm ≧ Vegrm−Kegr (that is, it is determined that the actual EGR control valve closing speed is not surely faster than the current reference EGR control valve closing speed), and the routine is executed. When the routine proceeds to step 315C, the actual EGR control valve closing speed is not surely higher than the current reference EGR control valve closing speed, so that the target EGR control valve opening is allowed to increase and is referred to The EGR control valve closing speed needs to be updated, and the reference throttle valve closing speed needs to be updated because the reference throttle valve closing speed cannot be said to be substantially equal to the actual throttle valve closing speed. Therefore, in step 315C, the target EGR control valve opening degree TXegr is increased, and then in step 315D, the current reference slot is increased. The toll valve closing speed Vthrr is updated to the throttle valve closing speed Vthm calculated in step 307, and the current reference EGR control valve closing speed Vegrr is changed to the EGR control valve closing speed Vegrm calculated in step 307. It is updated and the routine ends. In this case, the target EGR control valve opening obtained in step 18 of FIG. 8 is larger than the target EGR control valve opening so far.

  When it is determined in step 314A and step 315A that Vegrm <Vegrm−Kegr, the target EGR control valve opening is not increased and the reference EGR control valve closing speed and / or the reference throttle valve closing speed is not increased. Updates are made. The reason why such a correspondence is adopted when Vegrm <Vegrm−Kegr is as described above, but from another viewpoint, when Vegrm <Vegrm−Kegr, it is more than the increase in the target EGR control valve opening degree. It can be said that the priority is given to the updating of the reference EGR control valve closing speed and / or the reference throttle valve closing speed.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 33 ... Throttle valve, 50 ... Exhaust gas recirculation device (EGR device), 51 ... Exhaust gas recirculation passage (EGR passage), 52 ... Exhaust gas recirculation control valve (EGR control valve), 60 ... Electronic control device , T0 ... Deceleration request occurrence time, T1 ... Throttle valve opening start time, Tegrc ... EGR control valve closing time, Tegrcnew ... EGR control valve closing time after target EGR control valve opening increase, Tthc ... Throttle Valve closing time, Td ... predetermined delay time, Xth (T0) ... throttle valve opening when deceleration request occurs, Xegr (T0) ... EGR control valve opening when deceleration occurs, Xegrnew ... target EGR control valve opening EGR control valve opening when deceleration request occurs after increase, XthMin ... minimum throttle valve opening, XegrMin ... minimum EGR control valve opening, Legr ... EGR control Changes in the valve opening, Lth ... changes in the throttle valve opening, Legrnew ... Changes of the EGR control valve opening after increasing the target EGR control valve opening

Claims (3)

  A throttle valve disposed in the intake passage, and an exhaust gas recirculation device that introduces the exhaust gas discharged from the combustion chamber into the exhaust passage into the intake passage, thereby introducing the exhaust gas into the combustion chamber. Is a control device for an internal combustion engine having an exhaust gas recirculation control valve that controls the amount of exhaust gas introduced into the intake passage, and when the operating state of the internal combustion engine is in a normal operating state other than the deceleration operating state, The target amount as the amount of air to be inhaled is set as the target intake air amount, and the target amount as the amount of exhaust gas introduced into the intake passage by the exhaust gas recirculation control device is the target exhaust gas recirculation amount. The throttle valve opening and the exhaust recirculation control valve opening that can achieve the set target intake air amount and target exhaust recirculation amount are set respectively. The target throttle valve opening and the target exhaust gas recirculation control valve opening are set, and the throttle valve and the exhaust gas recirculation control valve are respectively controlled according to the set target throttle valve opening and target exhaust gas recirculation control valve opening, In a control device for an internal combustion engine, when the deceleration operation request of the internal combustion engine is generated, the opening of the throttle valve is reduced to the minimum opening and the opening of the exhaust gas recirculation control valve is reduced to the minimum opening. Exhaust gas recirculation control when the opening of the exhaust gas recirculation control valve reaches its minimum opening is earlier than the time when the throttle valve opening reaches the minimum opening after the engine deceleration request is generated The operating state of the internal combustion engine is in a normal operating state within a range in which the time when the valve opening reaches the minimum opening is not delayed from the time when the throttle valve opening reaches the minimum opening. The target exhaust gas recirculation control valve opening degree that is set as the opening degree of the exhaust gas recirculation control valve that can achieve the target exhaust gas recirculation amount that is set when the internal combustion engine is in the normal operating state A control device for an internal combustion engine in which a target exhaust gas recirculation amount that is set when the engine is at   Exhaust gas recirculation control valve at which the closing speed of the exhaust gas recirculation control valve is predicted at the time until the opening degree of the exhaust gas recirculation control valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine When the valve closing speed of the engine is slower, the throttle valve opening reaches its minimum opening when the opening degree of the exhaust gas recirculation control valve reaches its minimum opening after generation of a deceleration operation request of the internal combustion engine. 2. The control apparatus for an internal combustion engine according to claim 1, wherein an increase in the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is prohibited even when the time is earlier than the time point.   Exhaust gas recirculation control valve at which the closing speed of the exhaust gas recirculation control valve is predicted at the time until the opening degree of the exhaust gas recirculation control valve reaches the minimum opening degree after the occurrence of the deceleration operation request of the internal combustion engine When the valve closing speed is faster, the throttle valve opening reaches its minimum opening when the opening degree of the exhaust gas recirculation control valve reaches its minimum opening after the occurrence of a deceleration operation request of the internal combustion engine. 3. The control device for an internal combustion engine according to claim 1, wherein an increase in the target exhaust gas recirculation control valve opening or the target exhaust gas recirculation amount is prohibited even when the time is earlier than the time point.

Images